1. Field of the Invention
The present invention relates to a surface emission apparatus, a light guide, and a method of manufacturing a light guide, and more particularly to a surface emission apparatus having an optical device for diffusing light, a light guide, and a method of manufacturing a light guide.
2. Description of the Related Art
Display apparatus such as liquid crystal display apparatus, organic Electro Luminescence (EL) display apparatus, or the like are advantageous in that they are thin and lightweight, and have a low power requirement.
Liquid crystal display apparatus have a display panel in the form of a liquid crystal panel including a liquid crystal layer sealed between a pair of substrates. The liquid crystal panel may be of the transmissive type which modulates and transmits therethrough illuminating light that is emitted from a surface emission apparatus such as a backlight disposed behind the liquid crystal panel. The modulated illuminating light displays an image on the front surface of the liquid crystal panel.
There has been proposed a liquid crystal panel incorporating light detecting devices that function as position sensors in addition to TFTs as pixel switching devices.
The proposed liquid crystal panel operates as follows: Visible light rays from a detectable element such as a user's finger or a stylus pen held in contact with the front surface of the liquid crystal panel are detected by the light detecting devices. Based on the date of the light detected by the light detecting devices, the position where the detectable element touches the front surface of the liquid crystal panel is identified. The liquid crystal device itself or an electronic equipment connected to the liquid crystal device performs a certain process based on the identified position.
The data of the detected light produced by the light detecting devices for identifying the position of the detectable element possibly contain a lot of noise because of visible light rays included in ambient light. If the liquid crystal panel displays a black image, then the light detecting devices which are mounted on a TFT array substrate find it difficult to detect visible light rays emitted from the detectable element. In such a case, the position of the detectable element may not accurately be detected.
To eliminate the above drawback, there has been proposed a technology for emitting invisible light rays, rather than visible light rays, such as an infrared radiation, from a surface emission apparatus (see, for example, Japanese Patent Laid-open No. 2005-275644).
With respect to light sources of visible light rays and light sources of invisible light rays, the number of lights is determined by the luminance of the display panel, power consumption limitations, or the sensitivity of the light detecting devices. Generally, the number of lights of light sources of invisible light rays is smaller than the number of lights of light sources of visible light rays.